The object of the present invention is a spectrograph which can be used in particular in the far ultraviolet.
Spectrography in the far ultraviolet is used for the analysis of samples, and particularly of samples made of refractory materials, through formation from the latter of a plasma in a chamber free of air, the plasma being observed by the spectrograph through a slot provided in a wall of the chamber.
In the far ultraviolet field, the spectral lines supplied by the diffraction grating which is part of the spectrograph are extremely numerous and it is a reason why, in industry, only pre-set spectrographs are known for quantitatively analyzing in an analysed sample the chemical elements fixed beforehand.
In practice, to each current metallic alloy corresponds a determined spectrograph with which the user may analyze quantitatively the elements fixed beforehand of the alloy, whether metals or metalloids.
Said spectrographs comprise photo-detectors, each of which corresponding to the quantitative analysis of an element, disposed on the points of a circle, so-called Rowland circle, where the characteristic radiations focus, corresponding to the used diffraction grating.
Although for laboratory work monochromators are known which comprise a photo-detector movably mounted on the Rowland circle so as to be able to determine for each point of the circle the intensity of the diffracted radiation, and therefore trace out profiles, it has not been possible till now to provide the industry with a spectrograph comprising mobile photo-detectors and thereby adaptable to the analysis of different metallic alloys.